Efficient 1,8- and 1,9-asymmetric inductions in the Grignard reaction of δ- and ɛ-keto esters of 1,1′-binaphthalen-2-ols with an oligoether tether as the 2′-substituent: application to the synthesis of (−)-malyngolide

Abstract

Efficient 1,8- and 1,9-asymmetric inductions in the Grignard reaction of podand-type δ- (3,4) and ε-keto esters (5,6) are achieved in the presence of MgBr2·OEt2 with up to 97 and 82% optical yields, respectively, by using 2′-[3-(2-methoxyethoxy)propoxy]-1,1′-binaphthalen-2-ol as the chiral auxiliary. The 1,8-asymmetric inductive Grignard reaction has been advantageously utilized in the key step of a synthesis of (−)-malyngolide.